Safety signal device



March 2, 1954 J. F. LEDERER 2,671,200

SAFETY SIGNAL DEVICE Filed Oct. 18, 1950 2 Sheets-Sheet l INVENToR. Lwww'Zzdzrer March 2, 1954 J. F.' LEDERER SAFETY SIGNAL DEVICE 2Sheets-Sheet 2 Filed 061;. 18. 1950 INVENToR. femme Fler/ref PatentedMar. 2, 1954 UNITED STATES FFICE 6 Claims.

This invention relates to a safety signal device and particularly to adevice for providing an immediate and accurate indication of thepresence of metallic particles in a lubricant.

The presence of foreign substances, such as metallic particles andgranular carbon in a continuous flow lubricating system is detrimentalto the engine or machine in which the lubricant is being utilized.Granular carbon and particularly metallic particles are of an abrasivenature which results in a scoring of machine parts which are normallyrequired to be held in extremely close tolerances. Thelscoring ofmachine parts and other damage resulting from the presence of abrasivemetallic particles oftentimes results in a. substantial rise inoperating temperatures, which, together with other resulting detrimentaleffects, may lead to rapid engine failures.

In engines generally, and particularly in those incorporating acontinuously circulating` iubri cant, the presence of metallic abrasivematerial is highly undesirable and is normally difficult to detectbefore considerable damage or engine failure results therefrom. This isparticularly true in aircraft engines where a departure from standardoperating conditions or engine failure may lead to great loss of lifeand damage to property.

This invention may be briefly described as a device for detecting andproviding an immediate indication cf the presence of metallic particlesin a continuously flowing lubricant, of suflicient sensitivity to detectthe presence of said particles before scoring and damage to closetolerance machine elements or engine failure results therefrom. Theinvention includes means for setting up an electric field of constantcharacteristics through which the lubricant is passed, with associatedmeans responsive to a change in said constant electric field resultingfrom the presence of metallic particles therein, for providing animmediate indication of the presence of said particles.

In order to increase the response, to the indicating mechanism, of verysmall or relatively few particles in the oil stream l' prefer to includemeans for appropriately charging the particles in advance. n

An object of this invention is to provide a safety signal device for thedetection of metallic parn ticles in a flowing lubricant.

Another object of this invention is to provide a simple and eiicientsafety signal device for the detection of metallic particles in afiowingV lubricant.

- Another object of this invention is to provide a simple andinexpensive device for providing a clear external indication when thepresence of metallic abrasive material in a lubricating system reaches apredetermined amount.

Another object of the invention is to render metallic particles in aflowing lubricant more readily detectable.

A further object of this invention is to combine in a flowing stream orclosed circuit of lubricating liquid means for charging the extraneousparticles such as metallic particles and quantitatively detecting thepresence of such particles to give warning in ample time to preventengine failure.

Other objects and advantages of the invention Will be pointed out in thefollowing disclosure and claims which disclose, by way of example, theprinciples of the invention and the preferred embodiments vof the safetydevice applying those principles.

Referring to the drawings:

Fig. 1 schematically illustrates the presently preferred embodiment ofthe invention;

Fig. 2 schematically illustrates an alternative embodiment of theinvention;

Fig. 3 schematically illustrates another alternative embodiment of theinvention;

Fig. 4 schematically illustrates another alternative embodiment of theinvention which includes means for both charging the particles andactivating the detection mechanism;

Fig. 5 is a slight modification of the condenser structure shown in Fig.4, and

Fig. 6 is another schematic diagram illustrating means for charging theparticles in a owing stream shown in conjunction with the detectionmethod of Fig. l but which may also be used in conjunction with any ofthe alternatives shown in Figs. 2 to 5, inclusive.

Referring to Fig. 1, there is illustrated a portionlof the lubricantcontaining line lil formed of non-magnetic material through which thelubricant or a portion thereof continuously flows. Encircling thelubricant containing line lil is a helical coil I2 connected to asuitable direct current source, such Aas the battery l fi, in serieswith the primary winding lli of the transformer I8.

The direct current source le connected in circuit With'the coil l2results in the formation of a magnetic eld of constant and uniformchar-' acteristics within the lubricant flowing in the non-magneticlubricant containing line it. The presence of particles of magneticmaterial, such as'small metallic particles, within the magnetic fieldvgenerated by the coil l2 results in a change winding lof thetransformer i8 resultinglr from the presence'of metallic particles inthe lubricant in the line it, results in a change in current flow in thesecondary Winding 22 which is used to vary the frequency of theoscillator 24. @e .Output 0l the oscillator 24 is fed into two stages ofconventional amplication 26 and 28 and the amplified output is fed intoa discriminator. QQ. 'I lie die; criminator circuit 30 provides avarying voltage output which is responsive to the change in vfre"-quency of the oscillator 24. The varying voltage output of. thediscriminatori 3Q is` used to actuate an attention arresting indicatingdevice 32, which. may be'a suitable light, buzzer, or other signalingdevice, through, for. example, a suitable holding relay,- to provide awarning. signal ofpredc termined duration.

In the above embodiment of the invention the. circuitsfor the oscillator24, the an'ipliiiers` 'it and 28, and the discriminator. 30, are ofconi/ten tional and well-knownconstruction, and, as no claim of noveltyis being directed to these circuits individually, they. are representedschernat` ically` in the drawings.

Fig. 2 illustrates an alternative embodiment of. the invention. Inthlsembodiment, there is illustrated a portion of'the liilcrican't`'containing line 40 formed ofnonemagnetic materiai through which thelubricant. or. a' portion thereof conv tinuously flows. Encircling. thelubricantl containing line 40 is a helical coil 42 connected to asuitable direct current source, such as the hattery. 44, in series'with"the"primary. winding 45 of a transformer 48.

A's. described above with respect to Fig. l, the direct current source4.4 connected in circuit with the coil 42` results.' in a formation ot amagnetic field of constant and uniform characteristics within the'vlubricant owing in the` non-magnetic lubricant containing line' 4,0.The. presence of a particle of magnetic material, such as. small meltallic particles, within the magnetic eld."gener. ated bythe coil 42.results' in the change in said magnetic field. The change in the'vmagnetic eld results in a change in the current 'flowing through thecircuit includ-ing the coil 42, the'A direct. current source 4&1 and the46 of the transformer 48.

Connected in circuit. with thefsecondary winding 50 of the transformer4iiar'e several stagesf of-` amplification 'such as tlie ampliers 52, 5tand 5,5. The change iniA current iiow. in theprimary winding 46 of.'vthe transformer 487resultingff-roni the presence ofmetallic particles inthe lubricant in the line 40 results in a change 'in current fiow' inthefsecondaryfwinding 5c. The change in curn rent iiow in the' secondarywinding 5l]` is utilizedto vary the. grid voltage in the amplifier 52A.1Said."

amplifier. 524 is biased so that, this change. in. grid voltageresultsin a correspondingy ampliiied outl put. Theampliiied output. ofstage 52;is further.

primary winding current flow resulting from the presence of metallicparticles in the line 40 and the output required to trigger theindicating device 58. The amplified output in the embodiment illustratedin the drawings of stage 56 is used to trigger an eye-arrestingindicating device 58 which may be a suitable light, buzzer, or othersignaling device, through, for example, a suitable holding relay toprovide a signal of predetermined duration.

In` the embodiment of the invention illustrated in Fig. 2,'the circuitsfor the amplifiers 52, 54 and 56 are of conventional and well-knownconstruction, and as no claim of novelty is being directedA toward thesecircuits individually, they are. represented schematically in thedrawing.

Y'Fig'f illustrates another alternative embodiment ot the invention. Inthis embodiment of the invention, there is illustrated a portion of alubricant containing line 62 through which the lubricant or a portionthereof continuously flows. Bounding the line 62 are a pair of condenserplates 64 and V615 positioned so that the lubricantl flowing in'the line62y serves as a dielectric therefor..` The condenser plates `(i4 and Siiare included in the circuit of a oscillatorkv 68 normallyfbiased toprovide a constant frequency output. The capacitancer of the condenser.formed by the plates 64 and 66- is a function ofl thedielectric materialinterposed therebetween, i. e. the lubricant flowing in the line 62; Thepresence of metallic 'particles in the lubricant fiowing'in the line E2results. in a change in the dielectric constant of the materialinterposed between the plates 6d and 66. The change in the dielectricconstant varies the capacityofthe condenser formed by. such plates 64and 6G and this variation in. capacity. is usedr to vary. the frequency.ofthe oscillator '58.

As'describe'd above in connection with Eig` l,

`. the "output of the oscillator. 68 is fed into` two rectl-y` or.through a'n intermediate holding relay..

to provide a signal of predetermined duration In this embodiment of theinvention, as in the embodiments illustrated in` Figs. 1 and 2fthecircuit arrangements of. the units. schematically. represented areconventional and of Well-known 1 construction.

Asillustrated in Fig. 4 a set of concentric cons denser `plates. Ilv oftubular. 'form are mountedl within' andfinsulated from a tube or 'pipe18 through which'particles "to be detected'putesI The 'condenserplates.v mlayl be` arranged asr fiatparallel sheets le' as shown inFig.' 5 and itl- 1eV plates are charged by a suitable sourceofelectricity. marked 80- in Fig. 4 and 8i inFig. 5.

The presence of the 'particles in passingl `oetween theplates fl act todisturb thechfarge in the condenser and this disturbanceor variation incapacity is recorded. or signaled by suitable apparatus such as avoltmeter 32 asin Eig. 4 orasan ammetcr 83 as in Fig. 5'.:

The inner Wall of the tube' or. pipe| maybev insulated by anyfsuitable`coating or. lining 84, means. for.. amplifyingv the indicationf such asdescribed in connection. with the` arrangement of:

Fig. lmay be employed.

The narticlesas. they. pass termali. the. Spaces between condenserplates will contact the plates and thus become charged which willmagnify the effect as they continue to pass on.

6 illustrates an alternative embodiment of the invention. In thisarrangement there illustrated portion ci a lubricant containing line orpipe 85 which is provided with an enlargement 35 having an insulatinglining 8l and mounted within the enlargement is a charged body tilhaving a corrugated or otherwise extended surface 39, the shape and sizeand mounting of the body being such as to provide adequate passage forthe lubricant. The body S3 is charged by a suitable electrical source 99so that the metallic or lilze particles in the stream will be chargedthey conta-ct the surface t9 of the body the charged particles continuethrough the line or pipe they influence the capacitance of a coneenserhaving plates 9i and 92 which bound the line and included in the circuitor" an oscillator 93, normally to provide a constant frequency output.capacitance or" the condenser formed by the plates 9| and 92 isa-iunction oi the dielectric material interposed therebetween, i. e. thelubricant flowing in the line. The presence of extraneous chargedparticles in the lubricant flowing in the line 35 results in a change inthe dielectric constant and thus varies the capacity of the denser whichin turn varies the frequency ci the oscillator 93.

The output of the oscillator 93 is fed into two stages of conventionalamplifica-tions 9d and and the amplified output thereof is fed into adiscriminator 93 which is used to actuate an sttention indicating deviceSi which may 'ee suitable light, buzzer or other signaling device.

This part of the embodiment of my invention corresponds to thearrangement already shown and described in connection with Fig. 3 andthe alternative arrangements of Figs. 1 and 2 may be substitutedtherefore if desired.

The advantage gained by the complete embodiment of my invention shown inFig. 6 arises from the fact that the particles in the lubrication streamare charged as they come in contact with the extended surface of thecharged body 98 and hence are more readily detected as they pass betweenthe condenser plates 9i and 92.

This application is a continuation-impart of my copending patentapplication Serial No. 159,303, filed May 1, 1959, for Safety SignalDevice, which is now abandoned.

It is to be understood that the invention is not limited to the specicembodiments herein shown and described but may be carried out in otherways without departure from its spirit.

Having thus described my invention, I claim:

1. Apparatus for the detection of extraneous solid particles in alubricant owing in a line comprising means within the line forcontacting and charging the particles as they ilow therein, meansassociated with the line containing the flowing lubricant and spacedfrom said charging means for extending a constant electric iieldthereacross, means responsive to a change in said electric neldresulting from the presence of the charged particles therein foreffecting an electrical change and an indicating device responsive tosaid electrical change for providing an external indication of thechange resulting from the presence of extraneous particles therein.

2. Apparatus for the detection of extraneous solid particles in alubricant comprising means disposed Within the iiow of lubricant forelectrically charging said extraneous particles, means associated withthe owing lubricant and spaced from said charging means for providing anelectric eld of constant characteristics through which the lubricantmust pass, means responsive to changes in said electric field resultingfrom the presence of charged particles therein for effecting anelectrical change of greater magnitude, and .an indicating deviceresponsive to said electrical change of greater magnitude for providingan external indication of the presence of said extraneous particles insaid lubricant.

3. Apparatus for detection of extraneous solid particles flowing in aline comprising an electrically charged body disposed within said owinglubricant for electrically charging said extraneous particles, a sensingdevice spaced from said charged body and positioned to provide aconstant electric field through which the flowing lubricant and thecharged particles therein must pass, means associated with said sensingdevice and responsive to changes in said electric iield resulting fromthe presence of the charged particles therein for effecting electricalchanges of greater magnitude, and an indicating device responsive tosaid electrical changes of greater magnitude for providing an externalindication of the presence of said extraneous particles in saidlubricant.

4. A method for detecting the presence of extraneous solid particles ina lubricant comprising the steps of charging said particles in saidlubricant and measuring a change in a constant electric eld throughwhich said lubricant and said charged particles pass to detect thepresence of said particles.

5. A method for detecting the presence of extraneous solid particles ina lubricant comprising the steps of charging said particles in saidlubricant, passing said lubricant and said charged particles through anelectric field of constant characteristics and measuring the change insaid field resulting from the presence of said charged particlestherein.

6. A method for detecting the presence of extraneous solid particles ina lubricant comprising the steps of charging a body disposed in thelubricant to place a charge on the extraneous particles therein, passingsaid lubricant and said charged particles through an electric field ofconstant characteristics and measuring the change in said eld resultingfrom the presence of said charged particles therein.

JEROME F. LEDERER.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,070,556 Strong Aug. 19, 1913 1,808,709 Blake June 2, 19311,973,414 Miller Sept. 11, 1934 2,228,293 Wurzbach Jan. 14, 19412,349,992 Schrader May 30, 1944 2,387,496 Cornelius Oct. 23, 19452,455,543 Williams Dec. 7, 1948 2,491,445 Cunningham et al. Dec. 13,1949 2,512,879 Roggensten June 27, 1950

